使用数据库查询填充微调器
我最近开始进行 android 和 java 开发的编程。目前我通过编写时间表应用程序进行训练。 我想从数据库中获取包含所有主题的列表（该表还包含教师和房间）并将它们放入旋转器中。 这就是我编写的代码
Cursor c = dba.fetchAllSubjects();
if (c.getCount() != 0) {
Spinner subjectSpinner = (Spinner) findViewById(R.id.newlesson_subject);
startManagingCursor(c);
String[] from = new String[]{DbAdapter.KEY_SUBJECT};
int[] to = new int[] {android.R.layout.simple_spinner_item};
SimpleCursorAdapter subjectAdapter =
new SimpleCursorAdapter(this, android.R.layout.simple_spinner_item, c, from, to);
subjectSpinner.setAdapter(subjectAdapter);
}
问题是，当单击微调器时，它会显示一个列表，其中包含与数据库条目一样多的项目，但该列表不显示名称（您可以说它是空的）。所以我可能把简单的光标适配器搞砸了，但我不知道是什么。
感谢您的帮助
I recently started programming for android and java development in general. Currently I train by writing a timetable app.
I want to get a list with all subjects from the db (the table also contains teacher and rooms) and put them into a spinner.
Thats the code I wrote
Cursor c = dba.fetchAllSubjects();
if (c.getCount() != 0) {
Spinner subjectSpinner = (Spinner) findViewById(R.id.newlesson_subject);
startManagingCursor(c);
String[] from = new String[]{DbAdapter.KEY_SUBJECT};
int[] to = new int[] {android.R.layout.simple_spinner_item};
SimpleCursorAdapter subjectAdapter =
new SimpleCursorAdapter(this, android.R.layout.simple_spinner_item, c, from, to);
subjectSpinner.setAdapter(subjectAdapter);
}
The problem is that when clicking on the spinner it shows a list with as much items as the db has entries, but the list doesn't show the names (you can say it's empty). So I probably messed something up with the simple cursor adapter, but I don't know what.
Thanks for your help
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您的错误在于在 to 整数数组中指定了错误的资源 ID。
您需要指定 TextView（或类似类型的视图）的 ID，而不是布局本身。将上面的行替换为：
You're error lies in specifying the wrong Resource ID in your to integer array.
You need to specify the ID of a TextView (or similarly typed view) and not the layout itself. Replace the line above with: